Circular dichroism (CD) is a spectroscopic method that provides information about both the secondary and tertiary structure of proteins and nucleic acids. CD is an optical technique used to detect molecules that interact differently with right and left circularly polarized light. The fact that most biological molecules are chiral means that applications for the use of CD in the characterization of important macromolecules is widespread. Proteins, peptides and nucleic acids absorb light in specific areas of the visible and ultraviolet regions due to groups in the molecule called chromophores. Thus CD can generate information about the secondary structure of biological macromolecules and also about the binding of ligands to the molecules, providing evidence of conformational change. Because of this, circular dichroism has become recognized in the last decade by a broad base of biomedical investigators. In this proposal, investigators at the Burnham Iintitute (including structural biologists, cell biologists, neurobiologists, glycobiologists, biochemists and oncologists) request funding to purchase a circular dichroism spectropolarimeter. The Burnham Institute (formerly La Jolla cancer Research Foundation) is a non-profit biomedical research institute and an NCI Cancer Center with a staff of 33 principal investigators. CD will provide unique capabilities needed to advance the studies of more than a dozen important proteins or peptides, including analyses to characterize stability, integrity and physical properties of proteins, to monitor protein refolding, to evaluate protein-nucleic acid and protein-peptide interactions and to test the effects of glycosylation on protein structure. The CD spectropolarimeter will be operated as a shared resource. An operator/manager has been identified who has significant experience using CD and will take responsibility for the day-to-day operation of the instrument. An internal advisory committee, chaired by the principal investigator of this application, will oversee the utilization and scientific output of the CD spectropolarimeter.